GB1599973A - Electric cooker - Google Patents

Description

(54) ELECTRIC COOKER (71) We, IMANISHI FLEXIBLE TUBE MFG. CO. LTD., a Japanese Corporate, of No. 13-22, 3-chome, Higashi-Nakamoto, Higashinari-ku, Osaka, Japan, do hereby declare this invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be described in and by the following statement:- This invention relates generally to an electric cooker and more particularly, to a slow cooker suitable for both domestic and commercial uses in cooking such food as stew, curry or the like which requires being cooked over a long time without getting scorched, and consisting essentially of a cooking pot and a case assembly thereof.

Amongst conventional known electric cookers are, what are called, the electric ceramic cookers or slow cookers which are divided into two broad types: the direct heating type having a fixed inner pot or ceramic pot, and the indirect heating type having a removable inner pot. In either type, the inner pot is almost completely housed in the body, i.e. the shell of the case assembly, and the heat source is provided at the bottom alone, the drum side alone, or at both the bottom and the drum side.

In the case of the conventional electric cooker of the foregoing type, the heat transmitted from the heating element is received by entire surface of the bottom wall of drum wall of the inner pot. In the conventional slow cooker, therefore, it can hardly be said that heat is efficiently transmitted from heat source to the food being cooked. More particularly, heat is transmitted by conduction from the heat source to the food inside the inner pot through the wall thereof, being introduced by convection to all parts of the food to heat those parts to a substantially uniform temperature; this process takes a considerably long time. Accordingly, the conventional slow cooker has a disadvantage in that it takes a long time to attain a cooking temperature.

According to the present ivention, there is provided an electric cooker comprising a case including a shell and an outer pot, an electric heat source within the shell and in contact with the outside surface of the bottom wall of said outer pot, and an inner pot arranged to be removably mounted in said outer pot, said inner pot including an upper drum portion, a cylindrical bottom portion and a terraced portion intermediate the upper drum portion and the cylindrical bottom portion, the cylindrical bottom portion having a diameter smaller than the upper drum portion and substantially equal to the diameter of the outer pot, and the cylindrical bottom portion having a depth substantially equal to the depth of the outer pot and less than the depth of the upper drum portion, the upper drum portion, the lower cylindrical portion and the terraced portion being integral with one another, and the cylindrical bottom portion being locatable in contact with the outer pot so as to act as a heat receiving portion when the inner pot is placed in the outer pot.

Thus the electric cooker of the present invention is intended to increase the heatreceiving area of the pot bottom and, in addition, to effectively and properly utilize heat transferred by radiation and convection thereby achieving an excellent thermal efficiency.

Further features of the invention appear from the following description of an embodiment of the invention given by way of example only and with reference to the drawings in which: Fig. 1 is a side elevation showing the external appearance of an electric cooker, Fig. 2 is a longitudinal sectional view of an inner pot and case assembly of the electric cooker shown in Fig. 1, and Fig. 3 is a partially cutaway front view of the inner pot of the cooker.

In the figures, a case assembly includes a shell 1, having an integral base plate 2, and an outer pot 3. The outer pot 3 may be produced by forming an aluminium plate into a cup shape by drawing, and then anodizing it for, for example, maintaining a heat reflection effect. The outer pot is smaller in diameter than the shell 1 being provided at its upper end with an upper edge portion 5 having a predetermined width so that the outside end of the upper edge portion 5 may be held by the upper edge of the shell 1. The upper edge portion 5 of the outer pot 3 is provided with a number of radiation holes 10 for radiating the heat transmitted from a heating element to be later described. A space 4 formed between the shell 1 and the outer pot 3 is filled with heat insulating material.

Reference numeral 6 designates a plane heating element provided in contact with almost all the outside surface of the bottom wall of the outer pot 3. The heating element 6 is adapted to heat the outer pot 3, transferring heat by conduction to an inner pot 7 placed in the outer pot 3 so as to heat the inner pot 7. The inner pot 7 may be made of, for instance, ceramics such as semi-porcelain or heat-resisting glass. The inner pot 7 is provided, at its lower portion in the vicinity of its bottom, with a terraced section 8 having substantially the same width as the upper edge portion 5 of the outer pot 3. The inner pot 7 is also provided, below the terraced section 8, with a cylindrical bottom section or heat-receiving bottom section 9 having a diameter of P being smaller than the diameter D of the upper drum section of the inner pot 7.In addition, the depth of the heat-receiving bottom section 9 of the inner pot 7 from the terraced section 8 to the pot bottom 9' is substantially equal to the depth from the upper surface of the upper edge portion 5 of the outer pot 3 to the inside surface of the bottom wall of the outer pot 3. Accordingly, when the inner pot 7 is placed on the outer pot 3, the downward-facing surface of the terraced section 8 of the inner pot 7 abuts against the upper edge portion 5 of the outer pot 3 to hold the inner pot 7 stable and to keep only the heat receiving bottom section 9 substantially concealed in the outer pot 3.

As mentioned above, the heat-receiving bottom section section 9 of the inner pot 7 is slightly smaller in diameter than the upper drum section of the inner pot 7. If the diameter of the section 9 is not less than half of the diameter of the upper drum section of the inner pot 7, the inner pot 7 can be removed and stably put on a table or the like without-tipping.

Before baking, the inside and outside surfaces of the inner pot 7 are usually coated with white or cream-coloured glaze and provided with designs. However, the outside surface of the heat-receiving section 9 of the inner pot 7 is preferably coated with black glaze in order to improve heat absorption.

The above-mentioned flat or plane heating element 6 is kept in contact with the outside surface of the bottom wall of the outer pot 3. The heating element 6 is held by a keep plate 11 and fixed to the outer pot 3 by tightly engaging a nut 13 with a screw rod 12 fixed to the outer pot 3 at its bottom centre and extending downward through the base plate 2. The plane heating element 6 is usually sandwiched in between a plurality of heat-resisting insulating plates (not shown).

With the above construction, if the plane heating element 6 provided beneath the outer pot 3 is energized to heat the outer pot 3, the inner pot 7 placed in the outer pot 3 is gradually heated by conduction. As mentioned above, only the heat-receiving bottom section 9, which has a diameter ç smaller than the diameter of the upper exposed drum section of the inner pot 7 and is positioned below the terraced section 8, is concealed in the outer pot 3 belonging to the case assembly A. Therefore, in the above heating process, the heat loss of the heating element 6 is nearly negligible and as a result the heating element 6 can attain a desired temperature in as short time with relatively small power consumption; in addition, heat radiation from the radiation holes 10 facilitates heating.

Accordingly, the cooking time of the food contained in the inner pot 7 can be decreased. Moreover, radiation heat can be absorbed more effectively by coating the outside surface of the heat-receiving bottom section 9 below the terraced section 8 of the inner pot 7 with black glaze. Thus, it can be said that the heat-receiving area is increased by an area equivalent to that of the cylindrical wall of the heat-receiving section 9 and therefore extra heat can be absorbed and transmitted correspondingly.

As mentioned above, the electric cooker has an outer pot provided in a case assembly, an inner pot of ceramics or the like adapted to be removably mounted on the outer pot, the inner pot having an upper drum portion, terraced portion and heatreceiving portion below the terraced portion and smaller in diameter than the upper drum portion so that only the heatreceiving section is concealed in the output pot when the inner pot is placed on the outer pot. Therefore, of the food contained in the inner pot, a small amount of food contained in the heat-receiving bottom portion can be heated locally and rapidly by the heating element provided beneath lower surface of the outer pot; as a result, the time required for transmitting heat to all the parts of the food being cooked in the inner pot is decreased.

The inner pot is adapted to be removably mounted on the outer pot and has a smalldiameter heat-receiving portion under the terraced portion, and therefore the heatreceiving area is locally increased and as a result heating can be accelerated; the heatreceiving bottom portion-is provided with a black outside surface, and therefore the thermal efficiency is greatly improved owing to its high absortion power for radiant heat; the heat-receiving bottom portion of the inner pot is made slightly smaller in diameter than the upper exposed drum portion thereof so that only the heatreceiving portion is concealed in the case assembly when the former is placed on the latter, and therefore the total height of the case assembly can be decreased with the result that the amount of materials for the case assembly can be decreased; the outer pot has an upper edge portion provided with a number of radiation holes properly arranged, and therefore the inner pot can be heated not only by the plane heating element through the bottom wall of the inner pot but also by heat transmitted to the terraced portion of the inner pot through the above radiation holes.

WHAT WE CLAIM IS: 1. An electric cooker comprising a case including a shell and an outer pot, an electric heat source within the shell and in contact with the outside surface of the bottom wall of said outer pot, and an inner pot arranged to be removably mounted in said outer pot, said inner pot including an upper drum portion, a cylindrical bottom portion and a terraced portion intermediate the upper drum portion and the cylindrical bottom portion, the cylindrical bottom portion having a diameter smaller than the upper drum portion and substantially equal to the diameter of the output pot, and the cylindrical bottom portion having a depth substantially equal to the depth of the outer pot and less than the depth of the upper drum portion, the upper drum portion, the lower cylindrical portion and the terraced portion being integral with one another, and the cylindrical bottom portion being locatable in contact with the outer pot so as to act as a heat receiving portion when the inner pot is placed in the outer pot.

2. An electric cooker as claimed in claim 1, wherein the cylindrical bottom portion is diameter than said shell and has an upper edge portion with a predetermined width, said upper edge portion being supported on the upper edge of the shell, said terraced portion of said inner pot being substantially equal in width to said upper edge portion of said outer pot, and the downward-facing surface of said terraced portion of said inner pot being brought into contact with the upper edge portion of said outer pot when said inner pot is placed in said outer pot so that the bottom portion is concealed in said outer pot.

3. An electric cooker as claimed in claim 2, wherein said upper edge portion of said outer pot is provided with a plurality of radiation holes so that heat may be transmitted by convection to the downward-facing surface of the terraced portion of said inner pot.

4. An electric cooker as claimed in claim 1, wherein the outside surface of said heatreceiving bottom portion of said inner pot is coated with black glaze.

5. An electric cooker as claimed in claim 1, wherein said cylindrical bottom portion is smaller in diameter and not less than half of the diameter of said upper drum portion.

6. An electric cooker substantially as described with reference to the drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. mounted on the outer pot and has a smalldiameter heat-receiving portion under the terraced portion, and therefore the heatreceiving area is locally increased and as a result heating can be accelerated; the heatreceiving bottom portion-is provided with a black outside surface, and therefore the thermal efficiency is greatly improved owing to its high absortion power for radiant heat; the heat-receiving bottom portion of the inner pot is made slightly smaller in diameter than the upper exposed drum portion thereof so that only the heatreceiving portion is concealed in the case assembly when the former is placed on the latter, and therefore the total height of the case assembly can be decreased with the result that the amount of materials for the case assembly can be decreased; the outer pot has an upper edge portion provided with a number of radiation holes properly arranged, and therefore the inner pot can be heated not only by the plane heating element through the bottom wall of the inner pot but also by heat transmitted to the terraced portion of the inner pot through the above radiation holes. WHAT WE CLAIM IS:

1. An electric cooker comprising a case including a shell and an outer pot, an electric heat source within the shell and in contact with the outside surface of the bottom wall of said outer pot, and an inner pot arranged to be removably mounted in said outer pot, said inner pot including an upper drum portion, a cylindrical bottom portion and a terraced portion intermediate the upper drum portion and the cylindrical bottom portion, the cylindrical bottom portion having a diameter smaller than the upper drum portion and substantially equal to the diameter of the output pot, and the cylindrical bottom portion having a depth substantially equal to the depth of the outer pot and less than the depth of the upper drum portion, the upper drum portion, the lower cylindrical portion and the terraced portion being integral with one another, and the cylindrical bottom portion being locatable in contact with the outer pot so as to act as a heat receiving portion when the inner pot is placed in the outer pot.

2. An electric cooker as claimed in claim 1, wherein the cylindrical bottom portion is diameter than said shell and has an upper edge portion with a predetermined width, said upper edge portion being supported on the upper edge of the shell, said terraced portion of said inner pot being substantially equal in width to said upper edge portion of said outer pot, and the downward-facing surface of said terraced portion of said inner pot being brought into contact with the upper edge portion of said outer pot when said inner pot is placed in said outer pot so that the bottom portion is concealed in said outer pot.

3. An electric cooker as claimed in claim 2, wherein said upper edge portion of said outer pot is provided with a plurality of radiation holes so that heat may be transmitted by convection to the downward-facing surface of the terraced portion of said inner pot.

4. An electric cooker as claimed in claim 1, wherein the outside surface of said heatreceiving bottom portion of said inner pot is coated with black glaze.

5. An electric cooker as claimed in claim 1, wherein said cylindrical bottom portion is smaller in diameter and not less than half of the diameter of said upper drum portion.

6. An electric cooker substantially as described with reference to the drawings.